Circulating RNA was previously demonstrated through the identification of tumour-derived transcripts in the plasma and serum of cancer patients. This finding inspired the detection of cell-free fetal mRNA in maternal plasma which in turn facilitated the development of promising non-invasive prenatal assessment strategies applicable to pregnancies regardless of fetal sex. / Finally, in the last study, I implemented what I have learnt from the analysis of circulating fetal RNA into the development of brain-derived RNA transcripts for detection in the plasma of patients who had sustained brain injuries. A systematic approach based on gene expression microarray analysis was adopted to search for circulating brain-specific mRNA markers. Transcripts showing high expression levels in brain tissues but low expression levels in peripheral blood were identified. However, the detectability of these brain-derived mRNA markers in both peripheral and jugular plasma was found to be low. Instead, concentrations of these mRNA markers were found to be higher in cerebral spinal fluid (CSF) from brain-injured than non-brain-injured patients. / In section IV of this thesis, I reviewed and modified the blood sample processing and plasma RNA extraction protocols that were previously practised, in an attempt to enrich circulating fetal RNA in maternal plasma. Besides mRNA, extraction protocols for microRNAs (miRNAs), a new class of circulating nucleic acid markers, were also evaluated. The modifications in the protocols that I introduced led to significant improvements in RNA yield and enhanced the accuracy and reliability of circulating RNA detection in plasma, especially for those marginally detectable transcripts. / Recently, in addition to maternal plasma, there have been studies by other research groups reporting the presence of placental/fetal mRNA in maternal whole blood. In the first part of this thesis, I studied a list of previously identified placental mRNA transcripts, including chorionic somatomammotropin hormone 1 (CSH1), KiSS-1 metastasis-suppressor (KISS1), placenta-specific 4 (PLAC4) and placenta-specific 1 (PLAC1) in maternal whole blood and determined if this whole blood-based approach offered advantages over maternal plasma analysis. The presence of KISS1, PLAC4 and PLAC1 in non-pregnant and post-partum blood samples as well as the confirmed maternal contribution of PLAC4 mRNA in maternal blood proved that most of the detected 'placental' mRNA molecules in maternal whole blood were of maternal origin. To explore if more pregnancy-associated circulating mRNA markers could be developed for maternal whole blood analysis, candidates were mined after performing gene expression microarray comparison of whole blood samples from pregnant and non-pregnant individuals. The pregnancy-specificity of the identified gene candidates was further investigated. However, their presence in non-pregnant whole blood and lack of clearance after pregnancy indicated that they were not "pregnancy-specific" markers. These data suggested that pregnancy specific transcripts could be more readily identified from maternal plasma than whole blood. / The results presented in this thesis have not only provided a foundation facilitating the precise and accurate detection of fetal-specific RNA markers but have also improved the current understanding of the biology of circulating RNA. / Heung, May Sze. / Advisers: Dennis Lo; Rossa Wk Chiu. / Source: Dissertation Abstracts International, Volume: 72-11, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 212-239). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344581 |
| Date | January 2009 |
| Contributors | Heung, May-sze., Chinese University of Hong Kong Graduate School. Division of Chemical Pathology. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xvii, 239 leaves : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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